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Instantaneous microwave frequency measurement with high-resolution based on stimulated Brillouin scattering
摘要： A novel photonic method of instantaneous microwave frequency measurement (IMFM) based on Stimulated Brillouin scattering (SBS) is proposed. The principle of the technique is the employment of SBS effect to amplify/attenuate two adjacent frequency components, which result in a definite amplitude comparison function (ACF). Using this technique, the frequency of an unknown RF signal can be precisely obtained. Experimental results show the measurement capability of the proposed method over a frequency range of 0.47–23 GHz with a higher resolution of 8 MHz.
关键词： Amplitude comparison functions,Microwave photonics,Instantaneous microwave frequency measurement,Stimulated Brillouin scattering
更新于2025-09-23 15:23:52
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Frequency Extension of Atomic Measurement of Microwave Strength Using Zeeman Effect
摘要： Measuring the field strength of an electromagnetic wave based on atomic quantum mechanics is expected to be an innovative method to realize stable and reliable measurements. However, the major issue of atomic measurements is that the measurable frequency is limited to the resonant frequency of atoms. Therefore, in this paper, we demonstrate the measurement at arbitrary frequencies using the Zeeman effect in a static magnetic field. A cesium vapor cell is placed in a static magnetic field of approximately 40 mT, which causes the resonant frequency of the cesium atom to shift from 9.2 to 8.2 GHz. In addition, the Rabi frequency due to the interaction between cesium atoms and microwaves is measured at the frequency of 8.2 GHz in this experiment.
关键词： frequency measurement,microwave measurements,metrology,microwave spectroscopy,electromagnetic measurements,Atom optics,atomic measurements,measurement standards
更新于2025-09-23 15:22:29
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Photonic approach for microwave frequency measurement using a silicon microring resonator
摘要： We propose and experimentally demonstrate a photonic measurement approach of microwave frequency with adjustable measurement ranges and low errors based on a silicon microring resonator (MRR). The key factor is that microwave photonic filters (MPFs) with high rejection ratios could be realized by a phase modulator, an optical filter and a silicon MRR. In the experiment, by adjusting the wavelength of the laser diode, tunable MPFs with rejection ratios beyond 60 dB are realized in order to construct different amplitude comparison functions (ACFs) with high frequency resolutions (30dB/GHz). According to the mapping relationships between the microwave frequency and power ratio of the ACF, the unknown microwave frequency could be measured. The experimental results show that microwave frequency could be measured from 10 GHz to 19 GHz with a measurement resolution of 0.08 GHz. In the future, the measurement ranges and frequency resolutions could be manipulated according to practical requirements. The photonic measurement method and compact device are significant in microwave systems.
关键词： on-chip microwave system,Microwave frequency measurement,adjustable measurement range
更新于2025-09-23 15:22:29
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An Improved Frequency Measurement Method from the Digital PLL Structure for Single-Phase Grid-Connected PV Applications
摘要： The Phase Locked Loop (PLL) technique has been studied to obtain the phase and frequency information in grid-connected distributed generations for the sake of synchronizing the grid voltage and the inverter output current. In particular, the line frequency information, such as the anti-islanding function, is very important for the grid connection requirement. This paper presents a novel frequency measurement method from the digital PLL control structure for single-phase grid-connected PV applications. The conventional PLL controller uses the phase information to calculate the frequency of PV inverter output voltage after every line cycle and has shown a relatively low accuracy. This paper uses the angular frequency to directly measure the frequency after every line cycle. To verify the validity of the proposed method compared with the conventional method, a simulation was conducted. According to the simulation results, the measurement error of the proposed method is 80 times lower than the conventional one.
关键词： phase locked loop,frequency measurement,photovoltaic generation,grid-connection,PV inverter
更新于2025-09-23 15:21:01
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50-GHz Repetition Gain Switching Using A Cavity-enhanced DFB Laser Assisted By Optical Injection Locking
摘要： This paper introduces the (cid:2) counter, a frequency counter—i.e., a frequency-to-digital converter—based on the linear regression (LR) algorithm on time stamps. We discuss the noise of the electronics. We derive the statistical properties of the (cid:2) counter on rigorous mathematical basis, including the weighted measure and the frequency response. We describe an implementation based on a system on chip, under test in our laboratory, and we compare the (cid:2) counter to the traditional (cid:3) and (cid:4) counters. The LR exhibits the optimum rejection of white phase noise, superior to that of the (cid:3) and (cid:4) counters. White noise is the major practical problem of wideband digital electronics, both in the instrument internal circuits and in the fast processes, which we may want to measure. With a measurement time τ , the variance is proportional to 1/τ 2 for the (cid:3) counter, and to 1/τ 3 for both the (cid:4) and (cid:2) counters. However, the (cid:2) counter has the smallest possible variance, 1.25 dB smaller than that of the (cid:4) counter. The (cid:2) counter ?nds a natural application in the measurement of the parabolic variance, described in the companion article in this Journal [vol. 63 no. 4 pp. 611–623, April 2016 (Special Issue on the 50th Anniversary of the Allan Variance), DOI 10.1109/TUFFC.2015.2499325].
关键词： noise,regression analysis,frequency measurement,instrumentation and measurement,time measurement,phase noise,Frequency estimation
更新于2025-09-23 15:19:57
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A multiple microwave frequency measurement based on stimulated Brillouin scattering in few-mode optical fiber
摘要： A novel multiple microwave frequency measurement method is proposed. The operational principle is based on stimulated Brillouin scattering (SBS) in few-mode fiber (FMF). Due to the existence of SBS between the different modes of FMF, there are several different Brillouin frequency shifts in the fiber. Thus, a microwave frequency can be measured using an existing technique; even if the difference in the unknown frequencies is twice that of one of the Brillouin frequency shifts, the frequencies can be distinguished from the acquired signal powers of different ports of a mode-division multiplexer.
关键词： Frequency measurement,Few-mode optical fiber,Stimulated Brillouin scatting
更新于2025-09-12 10:27:22
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Towards a Quantum Standard for Absolute Pressure Measurements in the Range 200 Pa to 20 kPa Based on a Superconducting Microwave Cavity
摘要： We present a novel pressure standard for helium gas based on the measurement of resonance frequencies of a superconducting cavity and ab initio calculations of the thermophysical properties of helium. It should improve significantly the accuracy of measurements in the range 200 Pa to 20 kPa.
关键词： Microwave measurement,superconductivity,precision measurements,pressure measurement,frequency measurement
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Optical Frequency Measurements at 1×10?18 Uncertainty with Ytterbium Optical Lattice Clocks
摘要： We describe ytterbium optical lattice clocks under development at NIST. This includes the characterization of optical frequency stability and uncertainty, as well as measurements between two independent clocks, at the 10-18 level. We also report on optical frequency ratio measurements with other optical clocks at NIST.
关键词： precision frequency,optical lattice,optical standard,ytterbium,frequency measurement,uncertainty,optical ratio,optical clock
更新于2025-09-10 09:29:36